using System;

namespace GFGGame
{
    // 替代 System.Lazy<T> 的简单实现
    // 替代 System.Lazy<T> 的简易实现
    public class SimpleLazy<T>
    {
        private readonly Func<T> _initializer;
        private T _value;
        private bool _isInitialized;
        private readonly object _lock = new object();

        public SimpleLazy(Func<T> initializer)
        {
            _initializer = initializer ?? throw new ArgumentNullException(nameof(initializer));
        }

        public T Value
        {
            get
            {
                if (!_isInitialized)
                {
                    lock (_lock)
                    {
                        if (!_isInitialized)
                        {
                            _value = _initializer();
                            _isInitialized = true;
                        }
                    }
                }

                return _value;
            }
        }

        public bool IsValueCreated => _isInitialized;
    }
}